Curable resin composition, resin molded body, and method for producing resin molded body

Abstract

Provided is a curable resin composition which makes it possible to obtain a resin molded body that is excellent in acid resistance even when calcium carbonate particles are used.　A curable resin composition according to the present invention comprises a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, wherein: the average particle size of the calcium carbonate particles is not less than 8.5 μm; and the calcium carbonate particle content is 40-240 parts by weight relative to 100 parts by weight of the total of the polyol compound and the isocyanate compound.

Description

Curable resin composition, resin molded article, and method for producing resin molded article

[0001] The present invention relates to a curable resin composition containing a polyol compound and an isocyanate compound, and also to a resin molded article containing a urethane resin and a method for producing the same.

[0002] In recent years, resin molded bodies have been used in place of wood and the like as structural materials for building materials and the like. For example, resin molded bodies are sometimes used as railway sleepers instead of wooden sleepers and concrete sleepers. Furthermore, resin molded bodies are sometimes used in place of wood and the like for applications other than sleepers.

[0003] As an example of such a resin molded product, Patent Document 1 below discloses a resin molded product molded from a resin composition containing 1% by weight to 15% by weight of glass fiber and 30% by weight to 85% by weight of fly ash having a diameter distribution of 5 μm to 200 μm. In addition, in the examples of Patent Document 1, a polyol compound, an isocyanate compound, a filler, glass fiber, and a catalyst are mixed in an extruder to prepare a resin composition, which is then extruded under pressure into a mold through the extruder head to produce a resin molded product.

[0004] Patent Document 2 below discloses a fiber-reinforced resin molded article (resin molded body) formed by foaming and curing a urethane resin composition. The urethane resin composition contains a urethane resin component, long glass fibers, and a filler having a specific gravity of 4.0 or more. In Patent Document 2, the content of the filler having a specific gravity of 4.0 or more is 15 to 70 parts by weight per 100 parts by weight of the urethane resin component.

[0005] Patent Document 3 listed below discloses a urethane resin foam molded article reinforced with long glass fibers in the longitudinal direction. The surface layer or back layer of the urethane resin foam molded article contains a urethane resin foam and a solid filler.

[0006] Patent Document 4 below discloses a curable resin composition containing a polyol compound, an isocyanate compound, reinforcing long fibers, and a filler. In the curable resin composition, the filler has a specific gravity of less than 4 and an average circularity of 0.65 or more.

[0007] WO2007 / 014332A2 JP 2003-41013 A JP 2001-246632 A WO2020 / 054056A1

[0008] Resin molded articles are sometimes placed outdoors for use, and are sometimes exposed to an acidic environment due to acid rain or the like.

[0009] In order to reduce the cost of resin molded bodies, it has been considered to use calcium carbonate particles as a filler, but the present inventors have found that when calcium carbonate particles are simply used, the acid resistance of the resin molded body is low and acid rain and the like easily penetrate into the resin molded body.

[0010] An object of the present invention is to provide a curable resin composition that can provide a resin molded product having excellent acid resistance despite the use of calcium carbonate particles. Another object of the present invention is to provide a resin molded product having excellent acid resistance despite the use of calcium carbonate particles, and a method for producing the same.

[0011] This specification discloses the following curable resin composition, resin molded article, and method for producing a resin molded article.

[0012] Item 1. A curable resin composition comprising a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, wherein the calcium carbonate particles have an average particle size of 8.5 μm or more, and the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound.

[0013] Item 2. The curable resin composition according to Item 1, wherein the calcium carbonate particles have an average particle size of 10 μm or more.

[0014] Item 3. The curable resin composition according to Item 1 or 2, wherein the surfaces of the calcium carbonate particles are not treated with a surface treatment agent.

[0015] Item 4. The curable resin composition according to any one of Items 1 to 3, wherein the reinforcing long fibers have a fiber length of 50 mm or more.

[0016] Item 5. The curable resin composition according to any one of Items 1 to 4, wherein the content of the reinforcing long fiber is 40 parts by weight or more and 380 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound.

[0017] Item 6. The curable resin composition according to any one of Items 1 to 5, wherein the reinforcing long fibers are long glass fibers.

[0018] Item 7. The curable resin composition according to any one of Items 1 to 6, wherein the volume content of the calcium carbonate particles is 6 vol% or more and 19 vol% or less, based on 100 vol% of the curable resin composition.

[0019] Item 8. The curable resin composition according to any one of Items 1 to 7, further comprising a foaming agent.

[0020] Item 9. A resin molded product comprising a urethane resin, reinforcing long fibers, and calcium carbonate particles, wherein the calcium carbonate particles have an average particle size of 8.5 μm or more, and the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the urethane resin.

[0021] Item 10. The resin molded article according to Item 9, wherein the calcium carbonate particles have an average particle size of 10 μm or more.

[0022] Item 11. The resin molded article according to Item 9 or 10, wherein the surfaces of the calcium carbonate particles are not treated with a surface treatment agent.

[0023] Item 12. The resin molded body according to any one of Items 9 to 11, wherein the volume content of the calcium carbonate particles is 6% by volume or more and 19% by volume or less, based on 100% by volume of the resin molded body.

[0024] Item 13. The resin molded article according to any one of Items 9 to 12, wherein the reinforcing long fibers have a fiber length of 50 mm or more.

[0025] Item 14. The resin molded article according to any one of Items 9 to 13, wherein the reinforcing long fibers are long glass fibers.

[0026] Item 15. The resin molded body according to any one of Items 9 to 14, wherein the volume content of the calcium carbonate particles is 6% by volume or more and 19% by volume or less, based on 100% by volume of the resin molded body.

[0027] Item 16. The resin molded article according to any one of Items 9 to 15, which is a foamed resin molded article.

[0028] Item 17. The resin molded article according to Item 16, wherein the urethane resin has an expansion ratio of 1.1 times or more and 5 times or less.

[0029] Item 18. The resin molded article according to any one of Items 9 to 17, which is a railroad tie.

[0030] Item 19. A method for producing a resin molded product according to any one of Items 9 to 18, comprising: a step of obtaining a first composition containing a polyol compound, an isocyanate compound, and calcium carbonate particles; an impregnation step of impregnating spaces between reinforcing long fibers with the first composition to obtain a curable resin composition; and a curing step of curing the curable resin composition in a mold, wherein the content of the calcium carbonate particles in the first composition is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound in the first composition.

[0031] Item 20. The method for producing a resin molded article according to Item 19, wherein the reinforcing long fibers have a fiber length of 50 mm or more.

[0032] Item 21. The method for producing a resin molded product according to Item 19 or 20, wherein in the impregnation step, the first composition is impregnated between the reinforcing long fibers so that the content of the reinforcing long fibers is 20 parts by weight or more and 150 parts by weight or less per 100 parts by weight of the first composition.

[0033] Item 22. The method for producing a resin molded article according to any one of Items 19 to 21, wherein the reinforcing long fibers are long glass fibers.

[0034] Item 23. The method for producing a resin molded product according to any one of Items 19 to 22, wherein the first composition contains a foaming agent, and in the curing step, the curable resin composition is foamed and cured in a mold.

[0035] Item 24. The method for producing a resin molded article according to any one of Items 19 to 23, which is a method for producing a resin molded article used as a sleeper.

[0036] The curable resin composition according to the present invention contains a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 8.5 μm or more. In the curable resin composition according to the present invention, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound. Because the curable resin composition according to the present invention has the above configuration, it is possible to obtain a resin molded product having excellent acid resistance, despite the use of calcium carbonate particles.

[0037] The resin molded product according to the present invention includes a urethane resin, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 8.5 μm or more. In the resin molded product according to the present invention, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the urethane resin. Because the resin molded product according to the present invention has the above configuration, it has excellent acid resistance despite the use of calcium carbonate particles.

[0038] FIG. 1 is a cross-sectional view schematically illustrating a resin molded product according to one embodiment of the present invention. FIG. 2 is a diagram illustrating a method for producing a resin molded product according to one embodiment of the present invention. FIG. 3 is an electron microscope photograph of calcium carbonate particles A (average particle size 22 μm) used in the examples. FIG. 4 is an electron microscope photograph of calcium carbonate particles X (average particle size 5.5 μm) used in the comparative examples. FIG. 5 shows the results of a test using acidic solution A in Example 1. FIG. 5( a) is a microscope photograph of the surface of an evaluation sample before immersion in acidic solution A, FIG. 5( b) is a microscope photograph of the surface of the evaluation sample after immersion in acidic solution A, FIG. 5( c) is a microscope photograph of a cross section of the evaluation sample after immersion in acidic solution A, and FIG. 5( d) is the result of elemental analysis of the evaluation sample after immersion in acidic solution A. FIG. 6 shows the results of a test using acidic solution A in Example 2. FIG. 6( a) is a micrograph of the surface of the evaluation sample before immersion in acidic solution A, FIG. 6( b) is a micrograph of the surface of the evaluation sample after immersion in acidic solution A, FIG. 6( c) is a micrograph of the cross section of the evaluation sample after immersion in acidic solution A, and FIG. 6( d) is the result of elemental analysis of the evaluation sample after immersion in acidic solution A. FIG. 7 shows the results of a test using acidic solution A in Example 3. FIG. 7( a) is a micrograph of the surface of the evaluation sample before immersion in acidic solution A, FIG. 7( b) is a micrograph of the surface of the evaluation sample after immersion in acidic solution A, FIG. 7( c) is a micrograph of the cross section of the evaluation sample after immersion in acidic solution A, and FIG. 7( d) is the result of elemental analysis of the evaluation sample after immersion in acidic solution A. FIG. 8 shows the results of a test using acidic solution A in Comparative Example 1. Fig. 8(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution A, Fig. 8(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution A, Fig. 8(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution A, and Fig. 8(d) shows the results of elemental analysis of the evaluation sample after immersion in acid solution A. Fig. 9 shows the results when a test was conducted using acid solution A in Comparative Example 2.FIG. 9( a) is a micrograph of the surface of the evaluation sample before immersion in acidic solution A, FIG. 9( b) is a micrograph of the surface of the evaluation sample after immersion in acidic solution A, FIG. 9( c) is a micrograph of a cross section of the evaluation sample after immersion in acidic solution A, and FIG. 9( d) is the result of elemental analysis of the evaluation sample after immersion in acidic solution A. FIG. 10 shows the results of a test using acidic solution B in Example 1. FIG. 10( a) is a micrograph of the surface of the evaluation sample before immersion in acidic solution B, FIG. 10( b) is a micrograph of the surface of the evaluation sample after immersion in acidic solution B, FIG. 10( c) is a micrograph of a cross section of the evaluation sample after immersion in acidic solution B, and FIG. 10( d) is the result of elemental analysis of the evaluation sample after immersion in acidic solution B. FIG. 11 shows the results of a test using acidic solution B in Comparative Example 1. Fig. 11(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution B, Fig. 11(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution B, Fig. 11(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution B, and Fig. 11(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution B. Fig. 12 shows the results of compressive strength obtained by a compression test on the evaluation samples before and after immersion in acid solution A in Examples 1 to 3 and Comparative Examples 1 and 2. Fig. 13 shows the results of compressive strength reduction rates obtained by a compression test on the evaluation samples before and after immersion in acid solution A in Examples 1 to 3 and Comparative Examples 1 and 2.

[0039] The present invention will be described in detail below.

[0040] [The Present Invention (First Invention)] This specification discloses the following present invention (first invention) (resin composition and resin molded article).

[0041] The curable resin composition according to the present invention comprises a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 8.5 μm or more, and a content of the calcium carbonate particles in the curable resin composition according to the present invention is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound.

[0042] The curable resin composition according to the present invention has the above-mentioned features, and therefore, can provide a resin molded article having excellent acid resistance, even though calcium carbonate particles are used.

[0043] A resin molded product obtained by molding a curable resin composition may be exposed to an acidic environment due to acid rain or the like. The present inventors have found that when the average particle size of calcium carbonate particles is small, the calcium carbonate particles tend to be densely packed on the surface of the resin molded product (when the resin molded product is a foamed resin molded product, the surface of the foamed resin molded product and the surface of the cell walls). The present inventors have also found that when the average particle size of calcium carbonate particles is small, the calcium carbonate particles are eluted by acid, and acid rain or the like tends to penetrate into the resin molded product.

[0044] On the other hand, in the curable resin composition according to the present invention, calcium carbonate particles having a relatively large average particle size are used in a specific content, so that the calcium carbonate particles are less likely to create resistance in the curable resin composition and the viscosity of the curable resin composition is less likely to increase. Therefore, the calcium carbonate particles are more likely to penetrate between the reinforcing long fibers and are more likely to be uniformly dispersed in the curable resin composition. As a result, a resin molded product in which the calcium carbonate particles are uniformly dispersed can be obtained. Furthermore, because calcium carbonate particles having a relatively large average particle size are used, the calcium carbonate particles are less likely to be completely eluted by acid. Therefore, the penetration of acid rain and the like into the resin molded product can be effectively suppressed, thereby improving the acid resistance of the resin molded product.

[0045] The urethane resin can be obtained by reacting the polyol compound with the isocyanate compound in the presence of a catalyst.

[0046] In the curable resin composition according to the present invention, the calcium carbonate particles preferably have an average particle size of 10 μm or more. When calcium carbonate particles having an average particle size of 10 μm or more are used, the effects of the present invention can be more effectively exhibited than when calcium carbonate particles having an average particle size of 8.5 μm or more but less than 10 μm are used. In other words, when calcium carbonate particles having an average particle size of 10 μm or more are used, a resin molded product having significantly excellent acid resistance can be obtained.

[0047] The resin molded article according to the present invention includes a urethane resin, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 8.5 μm or more, and a content of the calcium carbonate particles in the resin molded article according to the present invention is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the urethane resin.

[0048] The resin molded article according to the present invention has the above-mentioned configuration, and therefore has excellent acid resistance despite the use of calcium carbonate particles.

[0049] In the resin molded product according to the present invention, the calcium carbonate particles preferably have an average particle size of 10 μm or more. When calcium carbonate particles having an average particle size of 10 μm or more are used, the effects of the present invention can be more effectively exhibited than when calcium carbonate particles having an average particle size of 8.5 μm or more but less than 10 μm are used. In other words, when calcium carbonate particles having an average particle size of 10 μm or more are used, the acid resistance of the resin molded product is significantly superior.

[0050] The resin molded article according to the present invention can be obtained, for example, by curing the above-mentioned curable resin composition.

[0051] FIG. 1 is a cross-sectional view schematically showing a resin molded body according to one embodiment of the present invention.

[0052] The resin molded body 91 shown in Fig. 1 includes a urethane resin 92, reinforcing long fibers 93, and calcium carbonate particles 94. Fig. 1 shows a cross section along the fiber diameter direction of the reinforcing long fibers 93.

[0053] Hereinafter, the components contained in the curable resin composition according to the present invention and the components constituting the resin molded article according to the present invention will be described in detail.

[0054] [Polyol Compound] A polyol compound is a compound having two or more hydroxyl groups (—OH groups).

[0055] Examples of the polyol compound contained in the curable resin composition include polylactone polyols, polycarbonate polyols, aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, and polyether polyols. The polyol compound may be a polymer polyol. The polyol compound may be used alone or in combination of two or more.

[0056] Examples of the polylactone polyol include polypropiolactone glycol, polycaprolactone glycol, and polyvalerolactone glycol.

[0057] Examples of the polycarbonate polyol include a dealcoholization reaction product of a hydroxyl group-containing compound and a carbonate compound. Examples of the hydroxyl group-containing compound include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, and nonanediol. Examples of the carbonate compound include diethylene carbonate and dipropylene carbonate.

[0058] Examples of the aromatic polyol include bisphenol A, bisphenol F, phenol novolac, and cresol novolac.

[0059] Examples of the alicyclic polyol include cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol.

[0060] Examples of the aliphatic polyol include ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

[0061] Examples of the polyester polyol include dehydration condensates of polybasic acids and polyhydric alcohols, ring-opening polymerization products of lactones, and condensates of hydroxycarboxylic acids and polyhydric alcohols. Examples of the polybasic acids include adipic acid, azelaic acid, sebacic acid, terephthalic acid, isophthalic acid, and succinic acid. Examples of the polyhydric alcohols include bisphenol A, ethylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexane glycol, and neopentyl glycol. Examples of the lactones include ε-caprolactone and α-methyl-ε-caprolactone. Examples of the hydroxycarboxylic acids include castor oil and reaction products of castor oil and ethylene glycol.

[0062] Examples of the polyether polyol include ring-opening polymers of an active hydrogen compound having two or more active hydrogen atoms and an alkylene oxide. Examples of the alkylene oxide include ethylene oxide, propylene oxide, and tetrahydrofuran. The molecular weight of the active hydrogen compound is preferably small. Examples of the active hydrogen compound include diol compounds such as bisphenol A, ethylene glycol, propylene glycol, butylene glycol, and 1,6-hexanediol; triol compounds such as glycerin and trimethylolpropane; and amine compounds such as ethylenediamine and butylenediamine.

[0063] Examples of the polymer polyol include graft polymers in which an unsaturated organic compound is graft polymerized onto a polyol compound, polybutadiene polyol, modified polyols of polyhydric alcohols, and hydrogenated products thereof.

[0064] Examples of the polyol compound in the graft polymer include aromatic polyol, alicyclic polyol, aliphatic polyol, polyester polyol, polyether polyol, etc. Examples of the unsaturated organic compound in the graft polymer include acrylonitrile, styrene, methyl acrylate, methyl methacrylate, etc.

[0065] The modified polyols of the polyhydric alcohols include reaction modified products of polyhydric alcohols and alkylene oxides. Examples of the polyhydric alcohol include trihydric alcohols such as glycerin and trimethylolpropane; tetrahydric to octahydric alcohols such as pentaerythritol, sorbitol, mannitol, sorbitan, diglycerin, dipentaerythritol, sucrose, glucose, mannose, fructose, methyl glucoside, and derivatives thereof; phenolic compounds such as phenol, phloroglucin, cresol, pyrogallol, catechol, hydroquinone, bisphenol A, bisphenol F, bisphenol S, 1-hydroxynaphthalene, 1,3,6,8-tetrahydroxynaphthalene, anthrol, 1,4,5,8-tetrahydroxyanthracene, and 1-hydroxypyrene; polybutadiene polyols; castor oil polyols; (co)polymers of hydroxyalkyl (meth)acrylates; polyfunctional polyols (for example, having 2 to 100 functional groups) such as polyvinyl alcohol; and condensates (novolaks) of phenol and formaldehyde. The alkylene oxide includes alkylene oxides having 2 or more and 6 or less carbon atoms. Specific examples of the alkylene oxide include ethylene oxide, 1,2-propylene oxide, 1,3-propylene oxide, 1,2-butylene oxide, and 1,4-butylene oxide. From the viewpoint of improving properties and reactivity, the alkylene oxide is preferably 1,2-propylene oxide, ethylene oxide, or 1,2-butylene oxide, and more preferably 1,2-propylene oxide or ethylene oxide. The alkylene oxides may be used alone or in combination of two or more.

[0066] When two or more kinds of the alkylene oxides are used, the addition may be in the form of block addition, random addition, or both block addition and random addition.

[0067] From the viewpoint of improving the dispersibility of calcium carbonate particles, the polyol compound is preferably a polyester polyol or a polyether polyol.

[0068] The viscosity of the polyol compound at 12° C. is preferably 200 cps or more, more preferably 300 cps or more, and preferably 1000 cps or less, more preferably 800 cps or less. When the viscosity is equal to or more than the above lower limit and equal to or less than the above upper limit, the calcium carbonate particles are more likely to impregnate between the reinforcing long fibers in the curable resin composition, and the abrasion resistance, flexural modulus, flexural strength, and compressive strength of the resin molded product can be improved.

[0069] The viscosity at 12°C can be measured using, for example, a Brookfield viscometer.

[0070] [Isocyanate Compound] An isocyanate compound is a compound having one or more isocyanate groups (-NCO groups).

[0071] Examples of the isocyanate compound contained in the curable resin composition include aromatic polyisocyanates, alicyclic polyisocyanates, and aliphatic polyisocyanates. From the viewpoint of efficiently progressing the curing reaction, the isocyanate compound is preferably a polyisocyanate compound. The isocyanate compounds may be used alone or in combination of two or more.

[0072] Examples of the aromatic polyisocyanate include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate.

[0073] Examples of the alicyclic polyisocyanate include cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and dimethyldicyclohexylmethane diisocyanate.

[0074] Examples of the aliphatic polyisocyanate include methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate.

[0075] The isocyanate compound is preferably diphenylmethane diisocyanate because it is easily available and has excellent convenience.

[0076] The polyol compound and the isocyanate compound can be used in appropriate amounts so as to efficiently form urethane bonds. From the viewpoint of improving reaction efficiency, the content of the isocyanate compound is preferably 100 parts by weight or more, more preferably 120 parts by weight or more, even more preferably 130 parts by weight or more, and preferably 180 parts by weight or less, more preferably 160 parts by weight or less, and even more preferably 150 parts by weight or less, relative to 100 parts by weight of the polyol compound. When the content of the isocyanate compound is equal to or more than the above lower limit and equal to or less than the above upper limit, the amount of unreacted polyol compound or unreacted isocyanate compound is reduced, and a resin molded product having even better flexural modulus, flexural strength, and compressive strength is easily formed.

[0077] [Reinforcing Long Fiber] The reinforcing long fiber is a reinforcing fiber, a long fiber. The reinforcing fiber is a fibrous material having a certain strength. Known reinforcing fibers include, for example, carbon fiber, glass fiber, and aramid fiber. The fiber length of the long fiber is, for example, an average fiber length of 50 mm or more. The reinforcing long fiber may be a reinforcing long fiber sheet.

[0078] Examples of the reinforcing long fibers contained in the curable resin composition and the resin molded product include carbon long fibers, glass long fibers, aramid long fibers, and long reinforcing fibers. The reinforcing long fibers may be used alone or in combination of two or more.

[0079] From the viewpoint of further increasing the flexural modulus, flexural strength, and compressive strength of the resin molded article, the reinforcing long fibers are preferably long glass fibers, which are fibrous materials obtained by melting and drawing glass.

[0080] From the viewpoint of further increasing the flexural modulus, flexural strength, and compressive strength of the resin molded article, the fiber length of the reinforcing long fibers is preferably 50 mm or more, more preferably 70 mm or more. The reinforcing long fibers can be cut to a desired size after pultrusion molding, and the fiber length of the reinforcing long fibers can be appropriately changed depending on the cutting length, so there is no particular upper limit to the fiber length of the reinforcing long fibers. Even if the reinforcing long fibers are long, they can be made less susceptible to breakage or entanglement by impregnating them with a composition containing components other than the reinforcing long fibers. Pultrusion molding also enables molding even when the blending ratio of the reinforcing long fibers is increased. The fiber length of the reinforcing long fibers may be equal to or less than the maximum length of the resin molded article, and may be 10,000 mm or less, 1,000 mm or less, or 500 mm or less.

[0081] The reinforcing long fibers are preferably rovings of monofilaments. The fiber diameter of the monofilaments is preferably 1 μm or more, more preferably 2 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less.

[0082] The average fiber diameter of the reinforcing long fibers is a number-average fiber diameter, which is the arithmetic mean value of the fiber diameters of 100 randomly selected fibers. The fiber diameter means the diameter of a circle equivalent to a cross section of the reinforcing long fibers taken along a direction perpendicular to the longitudinal direction of the reinforcing long fibers.

[0083] The content of the reinforcing long fiber is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, preferably 380 parts by weight or less, more preferably 300 parts by weight or less, and even more preferably 200 parts by weight or less, relative to 100 parts by weight of the total of the polyol compound and the isocyanate compound. When the content of the reinforcing long fiber is equal to or greater than the lower limit, the flexural modulus, flexural strength, and compressive strength of the resin molded article can be further increased. When the content of the reinforcing long fiber is equal to or less than the upper limit, the composition (first composition) containing the polyol compound, the isocyanate compound, and the calcium carbonate particles can be easily impregnated between the reinforcing long fibers, thereby more effectively achieving the effects of the present invention. In addition, the abrasion resistance, flexural modulus, and processability of the resin molded article can be improved.

[0084] The volume content of the reinforcing long fibers in 100% by volume of the resin molding is preferably 6% by volume or more, more preferably 8% by volume or more, and preferably 25% by volume or less, more preferably 20% by volume or less. When the volume content of the reinforcing long fibers is equal to or more than the above lower limit and equal to or less than the above upper limit, the flexural modulus, flexural strength, and compressive strength of the resin molding can be further increased.

[0085] The volume content of the reinforcing long fibers can be determined in accordance with the sintering method described in JIS K7052.

[0086] The reinforcing long fibers are preferably uniformly dispersed in the resin molded article. In the curable resin composition according to the present invention, a composition (first composition) containing a polyol compound, an isocyanate compound, and calcium carbonate particles is easily impregnated between the reinforcing long fibers, and the first composition is easily retained between the reinforcing long fibers. As a result, the reinforcing long fibers are easily dispersed uniformly in the resin molded article.

[0087] [Calcium Carbonate Particles] Calcium carbonate particles are a filler that is dispersed and filled in the resin portion of the resin molded body to reinforce the strength.

[0088] From the viewpoint of improving the flowability when molding the curable resin composition, the calcium carbonate particles are preferably powdery calcium carbonate particles. The calcium carbonate particles may be used alone or in combination of two or more types.

[0089] The surfaces of the calcium carbonate particles may or may not be treated with a surface treatment agent, such as barium sulfate.

[0090] From the viewpoint of reducing production costs, it is preferable that the surfaces of the calcium carbonate particles are not treated with a surface treatment agent. It is preferable that the calcium carbonate particles are surface-untreated, i.e., not treated with a surface treatment agent. In the present invention, calcium carbonate particles having a specific average particle size and content are used, and therefore the effects of the present invention can be achieved even when calcium carbonate particles not treated with a surface treatment agent are used.

[0091] From the viewpoint of exerting the effects of the present invention, the average particle size of the calcium carbonate particles is 8.5 μm or more. From the viewpoint of exerting the effects of the present invention more effectively, the average particle size of the calcium carbonate particles is preferably 10 μm or more.

[0092] The average particle size of the calcium carbonate particles is preferably 10 μm or more, more preferably 15 μm or more, more preferably 20 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. When the average particle size of the calcium carbonate particles is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the calcium carbonate particles are more easily dispersed uniformly in the curable resin composition, and a resin molded product in which the calcium carbonate particles are uniformly dispersed can be more effectively obtained. Furthermore, when the resin molded product is a foamed resin molded product, the calcium carbonate particles can be effectively prevented from crowding the cell walls. Therefore, when the average particle size of the calcium carbonate particles is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the effects of the present invention can be more effectively exhibited.

[0093] The average particle size of the calcium carbonate particles is the cumulative 50% diameter (D ５０ ) means

[0094] From the viewpoint of exerting the effects of the present invention, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound. Furthermore, when the content of the calcium carbonate particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the production cost of the resin molded article can be reduced. Furthermore, when the content of the calcium carbonate particles is equal to or more than the above lower limit, the flexural modulus, flexural strength, and compressive strength of the resin molded article can be increased.

[0095] The content of the calcium carbonate particles is preferably 50 parts by weight or more, more preferably 60 parts by weight or more, and preferably 150 parts by weight or less, more preferably 100 parts by weight or less, relative to 100 parts by weight of the total of the polyol compound and the isocyanate compound. When the content of the calcium carbonate particles is equal to or more than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the effects of the present invention can be more effectively exhibited, and the processability of the resin molded product can be improved. In addition, the production cost of the resin molded product can be reduced. Furthermore, when the content of the calcium carbonate particles is equal to or more than the above-mentioned lower limit, the flexural modulus, flexural strength, and compressive strength of the resin molded product can be increased.

[0096] From the viewpoint of exerting the effects of the present invention, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the urethane resin. Furthermore, when the content of the calcium carbonate particles is equal to or more than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the production cost of the resin molded body can be reduced. Furthermore, when the content of the calcium carbonate particles is equal to or more than the above-mentioned lower limit, the flexural modulus, flexural strength, and compressive strength of the resin molded body can be increased.

[0097] The content of the calcium carbonate particles relative to 100 parts by weight of the urethane resin is preferably 50 parts by weight or more, more preferably 60 parts by weight or more, and preferably 150 parts by weight or less, more preferably 100 parts by weight or less. When the content of the calcium carbonate particles is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the effects of the present invention can be more effectively exhibited, and the processability of the resin molded body can be improved. In addition, the production cost of the resin molded body can be reduced. Furthermore, when the content of the calcium carbonate particles is equal to or greater than the above-mentioned lower limit, the flexural modulus, flexural strength, and compressive strength of the resin molded body can be increased.

[0098] The volume content of the calcium carbonate particles in 100 volume% of the curable resin composition is preferably 6 volume% or more, more preferably 8 volume% or more, and preferably 19 volume% or less, more preferably 13 volume% or less. When the volume content of the calcium carbonate particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited. Furthermore, when the volume content of the calcium carbonate particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the flexural modulus of the resin molded product can be further increased.

[0099] The volume content of the calcium carbonate particles in 100 volume % of the resin molded body is preferably 6 volume % or more, more preferably 8 volume % or more, and preferably 19 volume % or less, more preferably 13 volume % or less. When the volume content of the calcium carbonate particles is equal to or more than the above lower limit and equal to or less than the above upper limit, the effects of the present invention can be more effectively exhibited. In addition, the flexural modulus of the resin molded body can be further increased.

[0100] The volume content of the calcium carbonate particles can be determined in accordance with the firing method described in JIS K7052.

[0101] [Blowing Agent] A blowing agent is a substance that generates a gas upon decomposition or that itself becomes a gas.

[0102] From the viewpoint of obtaining a foamed resin molded article, the curable resin composition preferably contains a foaming agent. The foamed resin molded article can be obtained by foaming the curable resin composition with the foaming agent. The foamed resin molded article has the advantage of being lighter than a non-foamed resin molded article.

[0103] When calcium carbonate particles with a small average particle size are used, the calcium carbonate particles tend to accumulate on the surface and cell walls of the foamed resin molding. Therefore, when the foamed resin molding comes into contact with acid rain or the like, the calcium carbonate particles dissolve, which facilitates cell interconnection, thereby allowing acid rain or the like to penetrate more easily into the foamed resin molding. In contrast, the curable resin composition of the present invention uses calcium carbonate particles with a relatively large average particle size at a specific content, which makes the calcium carbonate particles less likely to create resistance in the curable resin composition and less likely to increase the viscosity of the curable resin composition. This facilitates penetration of the calcium carbonate particles between the reinforcing long fibers and facilitates uniform dispersion of the calcium carbonate particles in the curable resin composition. As a result, a foamed resin molding in which the calcium carbonate particles are uniformly dispersed can be obtained. Furthermore, because calcium carbonate particles with a relatively large average particle size are used, the calcium carbonate particles are less likely to be completely dissolved by acid and less likely to form cell interconnections. This effectively prevents acid rain or the like from penetrating the foamed resin molding, thereby improving the acid resistance of the foamed resin molding. Therefore, when the curable resin composition contains a foaming agent and when the resin molded article is a foamed resin molded article, the effects of the present invention can be exhibited even more effectively.

[0104] Examples of the blowing agent include water and organic halogen compounds. Water is preferred as the blowing agent because it is easily available and has excellent convenience. Water reacts with an isocyanate compound to produce CO ２ The foaming agent acts as a foaming agent by generating a foam. The foaming agent may be used alone or in combination of two or more kinds.

[0105] Examples of the organic halogen compound include organic chlorine compounds, organic fluorine compounds, organic bromine compounds, and organic iodine compounds. The organic halogen compound may be an organic halogen compound in which all of the hydrogen atoms are substituted with halogen atoms, or an organic halogen compound in which some of the hydrogen atoms are substituted with halogen atoms. From the viewpoint of improving the foamability during the formation of a resin molded body and maintaining the thermal conductivity of the resin molded body at a low level for an even longer period of time, the organic halogen compound is preferably an organic chlorine compound or an organic fluorine compound.

[0106] Examples of the organic chlorine compound include saturated organic chlorine compounds and unsaturated organic chlorine compounds. Examples of the saturated organic chlorine compound include dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, and isopentyl chloride. From the viewpoint of improving the foaming properties during the formation of a resin molded body and maintaining the thermal conductivity of the resin molded body at a low level for an even longer period of time, the organic chlorine compound is preferably a saturated organic chlorine compound, and more preferably a saturated organic chlorine compound having 2 to 5 carbon atoms.

[0107] The organic fluorine compounds include saturated organic fluorine compounds and unsaturated organic fluorine compounds.

[0108] Examples of the saturated organic fluorine compounds include hydrofluorocarbons. Examples of the hydrofluorocarbon include difluoromethane (HFC32), 1,1,1,2,2-pentafluoroethane (HFC125), 1,1,1-trifluoroethane (HFC143a), 1,1,2,2-tetrafluoroethane (HFC134), 1,1,1,2-tetrafluoroethane (HFC134a), 1,1-difluoroethane (HFC152a), 1,1,1,2,3,3,3-heptafluoropropane (HFC227ea), 1,1,1,3,3-pentafluoropropane (HFC245fa), 1,1,1,3,3-pentafluorobutane (HFC365mfc), and 1,1,1,2,2,3,4,5,5,5-decafluoropentane (HFC4310mee).

[0109] Examples of the unsaturated organic fluorine compound include hydrofluoroolefins, such as 2,3,3,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene (HFO-1234ze) (E and Z isomers), and 1,1,1,4,4,4-hexafluoro-2-butene (HFO1336mzz) (E and Z isomers).

[0110] Further, the organic fluorine compound also includes a compound having a chlorine atom, a fluorine atom, and a double bond, such as 1,2-dichloro-1,2-difluoroethene (E and Z isomers) and hydrochlorofluoroolefins. Examples of the hydrochlorofluoroolefins include 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) (E and Z isomers), 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd) (E and Z isomers), 1-(4)chloro-1,3,3-trifluoropropene (HCFO-1233zb) (E and Z isomers), 2-chloro-1,3,3-trifluoropropene (HCFO-1233xe) (E and Z isomers), 2-chloro-2,2,3-trifluoropropene (HCFO-1233xc), and 2-chloro-3,3,3-trifluoropropene (HCFO-1233yd). 3-chloro-1,2,3-trifluoropropene (HCFO-1233xf), 3-chloro-1,2,3-trifluoropropene (HCFO-1233ye) (E and Z isomers), 3-chloro-1,1,2-trifluoropropene (HCFO-1233yc), 3,3-dichloro-3-fluoropropene, 1,2-dichloro-3,3,3-trifluoropropene (HCFO-1223xd) (E and Z isomers), 2-chloro-1,1,1,4,4,4-hexafluoro-2-butene (E and Z isomers), and 2-chloro-1,1,1,3,4,4,4-heptafluoro-2-butene (E and Z isomers).

[0111] From the viewpoint of improving the foaming properties during the formation of the resin molded body and maintaining the thermal conductivity of the resin molded body at a low level for an even longer period of time, the organic halogen compound is preferably a hydrochlorofluoroolefin, a hydrofluorocarbon, or a hydrofluoroolefin.

[0112] Taking foaming properties into consideration, the foaming agent can be used in an appropriate content. The content of the foaming agent relative to 100 parts by weight of the polyol compound is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, preferably 1.0 parts by weight or less, more preferably 0.8 parts by weight or less. When the content of the foaming agent is above the lower limit, foaming is promoted, a resin molded body is formed well, and dimensional defects of the resin molded body are less likely to occur. When the content of the foaming agent is below the upper limit, overflow of the curable resin composition from the mold due to excessive foaming can be prevented.

[0113] The expansion ratio of the urethane resin in the resin molded product is preferably 1.1 or more, more preferably 1.5 or more, and preferably 5 or less, more preferably 3 or less. When the expansion ratio is equal to or greater than the lower limit, a lightweight foamed resin molded product is likely to be obtained. When the expansion ratio is equal to or less than the upper limit, a foamed resin molded product having good flexural modulus, flexural strength, and compressive strength is likely to be obtained.

[0114] The expansion ratio of the urethane resin is determined by the volume V of the resin molded body, the weight W of the resin molded body, and the volume content V of the filler determined by the baking method of JIS K7052. filler and the weight of the filler W filler , and the volume content V of the reinforcing long fibers fiber and the weight W of the reinforcing long fibers fiber It should be noted that when the resin molding contains only the calcium carbonate particles as the filler, V filler and W filler are the volume content of calcium carbonate particles and the weight of calcium carbonate particles, respectively.

[0115] Foaming ratio of urethane resin = (1 - V filler -V fiber ) V / (W-W filler -W fiber)

[0116] V: Volume of resin molded body (cm ３ ) V filler V: Volume content of filler (volume %) fiber W: Weight of resin molding (g) filler W: Weight of filler (g) fiber : Weight of reinforcing long fiber (g)

[0117] [Catalyst] A catalyst is a substance that accelerates a chemical reaction.

[0118] The curable resin composition preferably contains a catalyst. Examples of the catalyst include a urethanization catalyst and a trimerization catalyst. The catalyst may be used alone or in combination of two or more.

[0119] The curable resin composition preferably contains a urethane-forming catalyst, which promotes the reaction between the hydroxyl group of the polyol compound and the isocyanate group of the isocyanate compound, thereby promoting the formation of a urethane bond.

[0120] Examples of the urethanization catalyst include organotin compounds such as dibutyltin dimaleate, dibutyltin diuralate, and dibutylbis(oleoyloxy)stannane; tertiary amine compounds such as triethylamine, N-methylmorpholinebis(2-dimethylaminoethyl)ether, and N,N,N',N",N"-pentamethyldiethylenetriamine; N,N,N'-trimethylaminoethyl-ethanolamine, bis(2-dimethylaminoethyl)ether, N-methyl,N'-dimethylaminoethylpiperazine; and imidazole compounds in which the secondary amine functional group in the imidazole ring is substituted with a cyanoethyl group. The urethanization catalyst may be used alone or in combination of two or more.

[0121] The urethanization catalyst can be used in an appropriate content so that the polyol compound and the isocyanate compound react well. The content of the urethanization catalyst is preferably 0.01 parts by weight or more, more preferably 0.02 parts by weight or more, and preferably 1.0 parts by weight or less, more preferably 0.8 parts by weight or less, relative to 100 parts by weight of the polyol compound. When the content of the urethanization catalyst is equal to or greater than the lower limit, the urethanization reaction proceeds effectively. When the content of the urethanization catalyst is equal to or less than the upper limit, the trimerization of the isocyanate group of the isocyanate compound is less likely to be inhibited.

[0122] The trimerization catalyst promotes the trimerization reaction of the isocyanate group of the isocyanate compound, promotes the formation of an isocyanurate ring, and further suppresses expansion of the resin molded article during combustion.

[0123] Examples of the trimerization catalyst include aromatic compounds, alkali metal salts of carboxylic acids, quaternary ammonium salts of carboxylic acids, and quaternary ammonium salt / ethylene glycol mixtures. Examples of the aromatic compounds include tris(dimethylaminomethyl)phenol, 2,4-bis(dimethylaminomethyl)phenol, and 2,4,6-tris(dialkylaminoalkyl)hexahydro-S-triazine. Examples of the alkali metal salts of carboxylic acids include potassium acetate and potassium 2-ethylhexanoate. The trimerization catalysts may be used alone or in combination of two or more.

[0124] The trimerization catalyst can be used in an appropriate content so as to satisfactorily promote the trimerization reaction. The content of the trimerization catalyst is preferably 0.01 parts by weight or more, more preferably 0.05 parts by weight or more, preferably 1.0 parts by weight or less, and preferably 0.8 parts by weight or less, relative to 100 parts by weight of the polyol compound. When the content of the trimerization catalyst is equal to or greater than the lower limit, expansion of the resin molded body during formation of the resin molded body is easily suppressed. When the content of the trimerization catalyst is equal to or less than the upper limit, the formation of urethane bonds is less likely to be inhibited.

[0125] [Other Components] The curable resin composition may contain other components such as a flame retardant, a foam stabilizer, and a filler other than calcium carbonate particles, as long as the object of the present invention is not impaired. The other components may be used alone or in combination of two or more.

[0126] The flame retardant is a substance that, when added to a flammable material such as plastic, wood, or fiber, can impart flame retardancy to the material.

[0127] Examples of the flame retardant include nitrogen-containing non-halogen flame retardants, red phosphorus, phosphate esters, phosphate-containing flame retardants, bromine-containing flame retardants, boron-containing flame retardants, antimony-containing flame retardants, metal hydroxides, etc. The flame retardants may be used alone or in combination of two or more.

[0128] The foam stabilizer is a substance that prevents the bubbles from becoming coarse and uneven, and enables the bubbles to be formed stably and favorably.

[0129] Examples of the foam stabilizer include polyoxyalkylene foam stabilizers such as polyoxyalkylene alkyl ethers, and silicone foam stabilizers such as organopolysiloxanes. The foam stabilizers may be used alone or in combination of two or more.

[0130] The foam stabilizer can be used in an appropriate content so as to stably and satisfactorily form bubbles. From the viewpoint of stably and satisfactorily forming bubbles, the content of the foam stabilizer is preferably 0.01 part by weight or more, more preferably 0.1 part by weight or more, even more preferably 0.2 part by weight or more, and preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and even more preferably 1 part by weight or less, relative to 100 parts by weight of the polyol compound.

[0131] Examples of fillers other than calcium carbonate particles include carbonate compounds, minerals, sulfate compounds, silicate compounds, clay, nitrides, carbon compounds, titanium compounds, metal borate compounds, sulfides, carbides, ash, sand, and pyroclastic debris. Only one type of filler other than calcium carbonate particles may be used, or two or more types may be used in combination.

[0132] (Other Details of Curable Resin Composition) The curable resin composition can be prepared by mixing the polyol compound, the isocyanate compound, the reinforcing long fibers, the calcium carbonate particles, and other components as necessary. The method for mixing the components is not particularly limited. A curable resin composition may be obtained by preparing multiple liquids containing one or multiple components and mixing the multiple liquids. The multiple liquids may be mixed when forming a resin molded product. The calcium carbonate particles and the isocyanate compound may be mixed with a liquid containing the polyol compound, and the reinforcing long fibers may be impregnated with this liquid. The calcium carbonate particles may be mixed with a liquid containing the polyol compound, and then the isocyanate compound may be mixed therewith, and the reinforcing long fibers may be impregnated with this liquid.

[0133] In the curable resin composition, the weight ratio of the content of the polyol compound to the content of the calcium carbonate particles (content of the polyol compound / content of the calcium carbonate particles) is designated as X. The viscosity at 12°C of a mixture obtained by mixing X parts by weight of the polyol compound with 1 part by weight of the calcium carbonate particles is preferably 7,000 cps or more, more preferably 13,000 cps or more, and preferably 60,000 cps or less, more preferably 45,000 cps or less. When the viscosity is equal to or greater than the above lower limit and equal to or less than the above upper limit, the calcium carbonate particles can more easily impregnate between the reinforcing long fibers in the curable resin composition, thereby improving the flexural modulus and abrasion resistance of the resin molded product.

[0134] The viscosity of the mixed liquid at 12° C. can be measured using, for example, a Brookfield viscometer.

[0135] (Resin Molded Article) A resin molded article can be obtained by molding and curing the curable resin composition according to the present invention. The resin molded article may be a foamed resin molded article. In this resin molded article, calcium carbonate particles are uniformly dispersed. This resin molded article has excellent acid resistance. In addition, this resin molded article has a high flexural modulus.

[0136] For example, the curable resin composition according to the present invention can be heated at 40° C. to 80° C., molded, and cured to obtain a resin molded article.

[0137] Normally, when a bending load is applied to a resin molded body in a direction axially parallel to the long fiber direction of the resin molded body, the resin molded body generally breaks due to the compressive load on the load side. This occurs because the compressive strength on the load side is weaker than the tensile strength on the opposite side. The resin molded body can increase its overall compressive strength, so that it exhibits high bending strength and compressive strength when a heavy object or the like is loaded from above.

[0138] Sleepers are buried in gravel, for example. Sleepers are required to have a high flexural modulus in order to reduce the amount of deflection change due to the load of the load. Furthermore, sleepers are required to have high acid resistance because they are used outdoors. The resin molded product has a good flexural modulus and acid resistance, and is therefore suitable for use as, for example, a sleeper. The resin molded product is preferably a sleeper. The curable resin composition is suitable for use in obtaining a sleeper.

[0139] When the resin molded article is used as a sleeper or the like, the size of the resin molded article is preferably 140 mm x 240 mm x 2600 mm (height (h) x width (w) x length (l)).

[0140] The height (h) is preferably 50 mm or more, more preferably 70 mm or more, even more preferably 90 mm or more, and is preferably 300 mm or less, more preferably 280 mm or less, even more preferably 260 mm or less.

[0141] The width (w) is preferably 50 mm or more, more preferably 100 mm or more, even more preferably 150 mm or more, and is preferably 300 mm or less, more preferably 280 mm or less, even more preferably 260 mm or less.

[0142] The length (l) is preferably 300 mm or more, more preferably 800 mm or more, even more preferably 1200 mm or more, and preferably 5000 mm or less, more preferably 3800 mm or less, even more preferably 3500 mm or less.

[0143] When the size of the resin molded body is equal to or larger than the lower limit and equal to or smaller than the upper limit, the resin molded body has a satisfactory flexural modulus as a sleeper.

[0144] The shape of the sleeper is not particularly limited. For example, it may be a rectangular parallelepiped sleeper, or may be a sleeper having a rectangular parallelepiped main body and a protrusion protruding outward from the main body.

[0145] The sleeper (resin molded article) may have a length direction and a width direction. From the viewpoint of further improving the bending modulus, bending strength, and compressive strength of the sleeper, it is preferable that the reinforcing long fibers are arranged along the length direction of the sleeper (resin molded article).

[0146] (Method for manufacturing resin molded body (sleeper)) The method for manufacturing a resin molded body according to the present invention preferably comprises the steps of obtaining a first composition containing a polyol compound, an isocyanate compound, and calcium carbonate particles, an impregnation step of impregnating spaces between reinforcing long fibers with the first composition to obtain a curable resin composition, and a curing step of curing the curable resin composition in a mold. In the method for manufacturing a resin molded body according to the present invention, the calcium carbonate particles have an average particle size of 8.5 μm or more. In the method for manufacturing a resin molded body according to the present invention, the calcium carbonate particles preferably have an average particle size of 10 μm or more.

[0147] 2 is a diagram for explaining a method for manufacturing a resin molded article according to one embodiment of the present invention, and is a diagram for explaining a method for manufacturing a resin molded article used as a sleeper.

[0148] The manufacturing apparatus 100 includes a hopper 11, a belt feeder 12, an extruder 4 with a built-in screw, a pump 43, a first raw material tank 21, a pump 22, a second raw material tank 31, a pump 51, a mixing and spraying device 5, a kneading plate 61, an impregnation plate 62, and a mold 63 with a heating section.

[0149] <Step of Obtaining First Composition> Calcium carbonate particles 1 are charged into a hopper 11, and then the calcium carbonate particles 1 are transported by a belt feeder 12 and supplied to an extruder 4. A first raw material 2 is charged into a first raw material tank 21 and mixed therewith. The first raw material 2 is a liquid containing a polyol compound and a foaming agent. The first raw material 2 is supplied to the extruder 4 by a pump 22. In the extruder 4, the calcium carbonate particles 1 and the first raw material 2 are mixed by the rotation of the screw of the extruder 4, thereby obtaining a mixed liquid of the calcium carbonate particles 1 and the first raw material 2 (hereinafter, sometimes referred to as "mixed liquid A"). The first raw material does not necessarily contain a foaming agent. The first raw material may contain a catalyst, a foam stabilizer, or both a catalyst and a foam stabilizer.

[0150] Since the average particle size of the calcium carbonate particles 1 is 8.5 μm or more, the stirring resistance can be reduced when mixing the calcium carbonate particles 1 with the first raw material 2, and the viscosity of the mixed liquid A can be kept low. As a result, the calcium carbonate particles 1 are more likely to be uniformly dispersed in the mixed liquid A. This effect is exhibited even when the average particle size of the calcium carbonate particles 1 is 0.1 μm or more, but is exhibited more effectively when the average particle size of the calcium carbonate particles 1 is 8.5 μm or more. From the viewpoint of exhibiting this effect even more effectively, it is preferable that the average particle size of the calcium carbonate particles 1 is 10 μm or more.

[0151] The second raw material 3 is charged into the second raw material tank 31. The second raw material 3 is an isocyanate compound.

[0152] The mixed liquid A is supplied to the mixing and spraying device 5 by the pump 43. The second raw material 3 is supplied to the mixing and spraying device 5 by the pump 51. In the mixing and spraying device 5, the mixed liquid A and the second raw material 3 are uniformly mixed to obtain a first composition 7 (a mixed liquid of a polyol compound, an isocyanate compound, calcium carbonate particles 1, and a foaming agent).

[0153] The content of the calcium carbonate particles 1 in the first composition 7 is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, even more preferably 60 parts by weight or more, and preferably 240 parts by weight or less, more preferably 150 parts by weight or less, and even more preferably 100 parts by weight or less, relative to 100 parts by weight of the total of the polyol compound and the isocyanate compound in the first composition 7. That is, in the step of obtaining the first composition 7, it is preferable to mix the polyol compound, the isocyanate compound, and the calcium carbonate particles 1 so that the content of the calcium carbonate particles 1 relative to 100 parts by weight of the total of the polyol compound and the isocyanate compound satisfies the above-mentioned preferable lower limit or upper limit.

[0154] Since the calcium carbonate particles 1 are well dispersed in the mixed liquid A, the calcium carbonate particles 1 are also likely to be uniformly dispersed in the first composition 7.

[0155] <Impregnation Step> The first composition 7 is sprayed onto the reinforcing long fiber bundles 8, which are fiber bundles of reinforcing long fibers, from the discharge port of the mixing and spraying device 5. It is preferable that the first composition 7 is sprayed onto the reinforcing long fiber bundles 8 while the reinforcing long fiber bundles 8 are moved in one direction. The reinforcing long fibers are long glass fibers, and the reinforcing long fiber bundles 8 are long glass fiber bundles.

[0156] The first composition 7 and the reinforcing long fiber bundles 8 are kneaded between the kneading plate 61 and the impregnation plate 62, and the first composition 7 is uniformly impregnated between the reinforcing long fibers constituting the reinforcing long fiber bundles 8. In this manner, a curable resin composition 81 is obtained.

[0157] Since the average particle size of the calcium carbonate particles 1 is 8.5 μm or more, the viscosity of the first composition 7 is relatively small. Therefore, when the reinforcing long fiber bundles 8 are impregnated with the first composition 7, the calcium carbonate particles 1 are easily dispersed among the reinforcing long fibers. Therefore, when the first composition 7 and the reinforcing long fiber bundles 8 are kneaded between the crumpling plate 61 and the impregnation plate 62, the first composition 7 is uniformly impregnated among the reinforcing long fibers. This effect is exhibited even when the average particle size of the calcium carbonate particles 1 is 0.1 μm or more, but is even more effectively exhibited when the average particle size of the calcium carbonate particles 1 is 8.5 μm or more. From the viewpoint of exhibiting this effect even more effectively, the average particle size of the calcium carbonate particles 1 is preferably 10 μm or more.

[0158] In the impregnation step, it is preferable that the first composition is impregnated between the reinforcing long fibers so that the content of the reinforcing long fibers is 20 parts by weight or more and 150 parts by weight or less per 100 parts by weight of the first composition.

[0159] <Curing Step> A foamed resin molded body can be produced by foaming and curing the curable resin composition 81 in the mold 63. More specifically, the curable resin composition 81 is transferred to the mold 63, and the curable resin composition 81 is foamed and cured in the mold 63, thereby producing a foamed resin molded body corresponding to the shape of the mold 63. Note that by sequentially transferring the curable resin composition 81 to the mold 63, foamed resin molded bodies can be continuously produced.

[0160] In addition, if the curable resin composition 81 does not contain a foaming agent, the curable resin composition 81 can be cured in the mold 63 to produce a resin molded body that corresponds to the shape of the mold 63.

[0161] As described above, since the present invention uses specific calcium carbonate particles, the calcium carbonate particles 1 can be favorably dispersed in the curable resin composition 81, and the calcium carbonate particles 1 can be favorably dispersed in the obtained resin molded body. Furthermore, the present invention allows the calcium carbonate particles 1 to be favorably impregnated between the reinforcing long fibers even when the amount of reinforcing long fibers used is increased, and therefore the calcium carbonate particles 1 can be favorably dispersed in the obtained resin molded body. As a result, the acid resistance and flexural modulus of the obtained resin molded body can be improved.

[0162] Furthermore, the method for producing a resin molded article according to the present invention can provide a resin molded article with small variations in flexural modulus, flexural strength, and compressive strength.

[0163] [Second Invention] Resin molded products are sometimes processed using a metal drill or the like. Conventional resin molded products may not be processed well with a metal drill. Furthermore, conventional resin molded products may wear out the metal drill used to process the resin molded product.

[0164] For example, Japanese Patent Application Laid-Open No. 2001-246632 discloses the use of the above-mentioned solid filler to increase the compressive strength and flexural strength of a urethane resin foam molded product. In the examples of Japanese Patent Application Laid-Open No. 2001-246632, No. 7 silica sand is used as the solid filler. Even if the compressive strength and flexural strength of the resin molded product can be increased when such No. 7 silica sand is used, the metal drill is likely to wear out when the resin molded product is machined with the metal drill. As a result, continuous and stable drilling may not be possible.

[0165] This specification also discloses the following second invention (resin composition and resin molded article).

[0166] An object of the second invention is to provide a curable resin composition that can give a resin molded article having excellent processability. Another object of the second invention is to provide a resin molded article having excellent processability and a method for producing the same.

[0167] Curable resin composition of a second invention: A curable resin composition comprising a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, wherein the calcium carbonate particles have an average particle size of 0.1 μm or more, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound, and the volume content of the calcium carbonate particles is 6% by volume or more and 19% by volume or less in 100% by volume of the curable resin composition.

[0168] That is, the curable resin composition according to the second invention comprises a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 0.1 μm or more. In the curable resin composition according to the second invention, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound. The volume content of the calcium carbonate particles is 6% by volume or more and 19% by volume or less in 100% by volume of the curable resin composition according to the second invention.

[0169] Resin molded bodies are sometimes processed using metal drills or the like. Conventional resin molded bodies may not be processed well with metal drills. As a result, continuous and stable drilling may not be possible. Furthermore, conventional resin molded bodies may wear out the metal drills used to process the resin molded bodies. Furthermore, fillers are considered to be used to increase the compressive strength and bending strength of resin molded bodies. However, resin molded bodies containing fillers may have poor processability, particularly with metal drills. In particular, depending on the type of filler, resin molded bodies containing 6% or more by volume of filler per 100% by volume of the resin molded body may have significantly poor processability.

[0170] The curable resin composition according to the second invention has the above-mentioned features, and therefore can provide a resin molded article with excellent processability.

[0171] Furthermore, the curable resin composition according to the second invention uses specific calcium carbonate particles, which can increase the bending strength and compressive strength of the resulting resin molded product. Furthermore, calcium carbonate is a relatively inexpensive filler. The curable resin composition according to the second invention can reduce the cost of the resulting resin molded product while improving processability and increasing the bending strength and compressive strength.

[0172] Furthermore, in the curable resin composition according to the second invention, since the composition has the above-described configuration, and in particular since the filler is specific calcium carbonate particles, even if the content of the filler in 100% by volume of the curable resin composition is 6% by volume or more, the curable resin composition can be well processed with a metal drill or the like. In the curable resin composition according to the second invention, even if the content of the filler in 100% by volume of the curable resin composition is 6% by volume or more, the obtained resin molded article can be well processed continuously and stably with a metal drill or the like. In addition, in the curable composition according to the second invention, since the volume content of the calcium carbonate particles in 100% by volume of the curable resin composition is 19% by volume or less, the obtained resin molded article can be well processed continuously and stably with a metal drill or the like.

[0173] In the curable resin composition according to the second invention, the average particle size of the calcium carbonate particles may be 0.1 μm or more. In the curable resin composition according to the second invention, the average particle size of the calcium carbonate particles may be 0.1 μm or more and less than 8.5 μm. In the curable resin composition according to the second invention, if the average particle size of the calcium carbonate particles is 0.1 μm or more and less than 8.5 μm, it is difficult to obtain a resin molded product having excellent acid resistance, but it is possible to obtain a resin molded product having excellent processability. In the second invention, since the effect of excellent processability is exerted, the effect of excellent acid resistance does not necessarily have to be exerted. From the viewpoint of obtaining a resin molded product having excellent not only processability but also acid resistance, in the curable resin composition according to the second invention, the average particle size of the calcium carbonate particles is preferably 8.5 μm or more, and more preferably 10 μm or more.

[0174] Resin molded body of a second invention: A resin molded body comprising a urethane resin, reinforcing long fibers, and calcium carbonate particles, wherein the calcium carbonate particles have an average particle size of 0.1 μm or more, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the urethane resin, and the volume content of the calcium carbonate particles is 6% by volume or more and 19% by volume or less in 100% by volume of the resin molded body.

[0175] A resin molded product according to a second aspect of the present invention includes a urethane resin, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 0.1 μm or more. In the resin molded product according to the second aspect of the present invention, the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the urethane resin. The volume content of the calcium carbonate particles in 100 volume percent of the resin molded product according to the second aspect of the present invention is 6 volume % or more and 19 volume % or less.

[0176] The resin molded article according to the second aspect of the present invention has the above-described structure and is therefore excellent in processability.

[0177] Furthermore, the resin molded product according to the second invention uses specific calcium carbonate particles, which allows the resin molded product to have increased bending strength and compressive strength. Furthermore, calcium carbonate is a relatively inexpensive filler. The resin molded product according to the second invention allows the resin molded product to have improved processability and increased bending strength and compressive strength while reducing the cost of the resin molded product.

[0178] Furthermore, since the resin molded body according to the second invention has the above-mentioned configuration, and in particular since the filler is specific calcium carbonate particles, the resin molded body can be well machined with a metal drill or the like even if the filler content in 100% by volume of the resin molded body is 6% by volume or more. The resin molded body according to the second invention can be well machined continuously and stably with a metal drill or the like even if the filler content in 100% by volume of the resin molded body is 6% by volume or more. Furthermore, since the volume content of the calcium carbonate particles in 100% by volume of the resin molded body is 19% by volume or less, the resin molded body can be well machined continuously and stably with a metal drill or the like.

[0179] In the resin molded product according to the second invention, the average particle diameter of the calcium carbonate particles may be 0.1 μm or more. In the resin molded product according to the second invention, the average particle diameter of the calcium carbonate particles may be 0.1 μm or more and less than 8.5 μm. In the resin molded product according to the second invention, if the average particle diameter of the calcium carbonate particles is 0.1 μm or more and less than 8.5 μm, it is difficult to achieve excellent acid resistance of the resin molded product, but the resin molded product has excellent processability. In the second invention, since the effect of excellent processability is exerted, the effect of excellent acid resistance does not necessarily have to be exerted. From the viewpoint of obtaining a resin molded product that is excellent not only in processability but also in acid resistance, in the resin molded product according to the second invention, the average particle diameter of the calcium carbonate particles is preferably 8.5 μm or more, and more preferably 10 μm or more.

[0180] Other details of the second invention: In order to achieve the effects of the second invention, particularly the effect of excellent processability, the calcium carbonate particles in the second invention have an average particle size of 0.1 μm or more.

[0181] In the second invention, the average particle size of the calcium carbonate particles is preferably 5 μm or more, more preferably 8.5 μm or more, even more preferably 10 μm or more, particularly preferably 15 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. When the average particle size of the calcium carbonate particles is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the calcium carbonate particles are more easily dispersed uniformly in the curable resin composition, and a resin molded product in which the calcium carbonate particles are uniformly dispersed can be obtained more effectively. Furthermore, when the resin molded product is a foamed resin molded product, the calcium carbonate particles can be effectively prevented from crowding the cell walls. Therefore, when the average particle size of the calcium carbonate particles is equal to or greater than the above-mentioned lower limit and equal to or less than the above-mentioned upper limit, the effects of the second invention can be more effectively exhibited. In the second invention, the average particle size of the calcium carbonate particles may be less than 10 μm or less than 8.5 μm.

[0182] The average particle size of the calcium carbonate particles means the cumulative 50% diameter (D50) in the particle size distribution based on the number of particles measured by a wet laser diffraction scattering method.

[0183] In the second aspect of the present invention, the volume content of the calcium carbonate particles is 6% by volume or more and 19% by volume or less, based on 100% by volume of the curable resin composition. With this curable resin composition, even if the filler content in 100% by volume of the curable resin composition is 6% by volume or more, it is possible to obtain a resin molded product with excellent processability. Furthermore, because the volume content of the calcium carbonate particles in 100% by volume of the curable resin composition is equal to or more than the lower limit and equal to or less than the upper limit, it is possible to reduce the cost of the resin molded product while improving processability and increasing the bending strength and compressive strength.

[0184] In the second aspect of the present invention, the volume content of the calcium carbonate particles in 100% by volume of the resin molded body is 6% by volume or more and 19% by volume or less. The resin molded body has excellent processability even when the content of the filler in 100% by volume of the resin molded body is 6% by volume or more. Furthermore, since the volume content of the calcium carbonate particles in 100% by volume of the resin molded body is equal to or more than the lower limit and equal to or less than the upper limit, the processability can be improved and the bending strength and compressive strength can be increased while reducing the cost of the resin molded body.

[0185] In 100% by volume of the curable resin composition according to the second invention and 100% by volume of the resin molded product according to the second invention, the volume content of the calcium carbonate particles is preferably 7% by volume or more, more preferably 8% by volume or more, and preferably 17% by volume or less, more preferably 15% by volume or less, even more preferably 13% by volume or less, and particularly preferably 12% by volume or less. Even if the volume content of the calcium carbonate particles is above the above-mentioned lower limit, the processability of the resin molded product can be sufficiently improved. When the content of the calcium carbonate particles is below the above-mentioned upper limit, the processability of the resin molded product can be further improved. Furthermore, when the volume content of the calcium carbonate particles is above the above-mentioned lower limit and below the above-mentioned upper limit, the bending strength and compressive strength of the resin molded product can be further improved. Furthermore, it is preferable to use calcium carbonate particles such that, after the above-mentioned series of steps (the step of obtaining the first composition, the impregnation step, and the curing step), the volume content of the calcium carbonate particles in 100% by volume of the resin molded product satisfies the above-mentioned preferred lower limit or upper limit.

[0186] The volume content of the calcium carbonate particles can be determined in accordance with the firing method described in JIS K7052.

[0187] The above-mentioned preferred configuration of the first invention applies to the configuration of the calcium carbonate particles of the second invention other than the average particle size and volume content.

[0188] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0189] The following materials were prepared:

[0190] (Polyol Compound) Polyether polyol ("M9158" manufactured by Sumika Covestro Urethane Co., Ltd., viscosity 500 cps at 12°C)

[0191] (Isocyanate compound) Diphenylmethane diisocyanate ("Polymeric MDI" manufactured by Sumika Covestro Urethane Co., Ltd., viscosity 200 cps at 12°C)

[0192] The viscosity of the polyol compound and the isocyanate compound at 12°C was measured using a Brookfield viscometer ("Digital Rotational Viscometer" manufactured by Viscotec).

[0193] (Filler) Calcium carbonate particles A ("Whiten H" manufactured by Shiraishi Calcium Co., Ltd., specific gravity 2.7, average particle size 22 μm, surface untreated) Calcium carbonate particles B ("Minex SP" manufactured by Shiraishi Calcium Co., Ltd., specific gravity 2.7, average particle size 15.5 μm, surface untreated) Calcium carbonate particles C ("Minex No. 4-F" manufactured by Shiraishi Calcium Co., Ltd., specific gravity 2.7, average particle size 8.5 μm, surface untreated) Calcium carbonate particles X ("Whiten P-30" manufactured by Shiraishi Calcium Co., Ltd., specific gravity 2.7, average particle size 5.5 μm, surface untreated) Calcium carbonate particles Y ("Whiten P-10" manufactured by Shiraishi Calcium Co., Ltd., specific gravity 2.7, average particle size 3.0 μm, surface untreated)

[0194] Electron microscope photographs of calcium carbonate particles are shown in Figures 3 and 4. Figure 3 is an electron microscope photograph of calcium carbonate particles A (average particle size 22 µm), and Figure 4 is an electron microscope photograph of calcium carbonate particles X (average particle size 5.5 µm).

[0195] (Reinforcing long fiber) Long glass fiber (a roving made by aligning many monofilaments with a fiber diameter of 6 to 20 μm)

[0196] (Foaming agent) Water

[0197] (Catalyst) Tertiary amine catalyst A (manufactured by Evonik Japan, "DABCO 33LV") Tertiary amine catalyst B (manufactured by San-Apro, "U-CAT SA1")

[0198] (Foam stabilizer) Silicone oil ("SZ-1729" manufactured by Toray Dow Silicone Co., Ltd.)

[0199] Example 1 A foamed resin molded article was produced by the method shown in FIG.

[0200] <Preparation of Curable Resin Composition> A polyol compound, a foaming agent, a catalyst, and a foam stabilizer were mixed to obtain the first raw material shown in FIG. 2. The first raw material was mixed with a filler (calcium carbonate particles A) to obtain a mixed solution A. An isocyanate compound, which is the second raw material, was added to and mixed with the obtained mixed solution A to obtain a first composition. The obtained first composition was impregnated between long glass fibers to prepare a curable resin composition. Each component was used in the blending amount (parts by weight) shown in Table 1 below.

[0201] (Production of resin molded body) The obtained curable resin composition was poured into a rectangular mold (length 400 mm × width 100 mm × height 65 mm), and then heated in an oven at 40°C for 50 minutes to foam-mold and harden, and a resin molded body (foamed resin molded body) was obtained from the mold.

[0202] (Examples 2 and 3 and Comparative Examples 1 and 2) Curable resin compositions and resin molded articles (foamed resin molded articles) were obtained in the same manner as in Example 1, except that the types of blending components used were changed as shown in Table 1 below.

[0203] (Evaluation) (1) Volume Content of Calcium Carbonate Particles and Long Glass Fibers The obtained resin molded body was cut into a size of 10 mm length × 10 mm width × 10 mm thickness. Using the cut resin molded body, the volume content of calcium carbonate particles in 100% by volume of the resin molded body and the volume content of long glass fibers in 100% by volume of the resin molded body were determined in accordance with the firing method described in JIS K7052.

[0204] (2) Expansion Ratio of Urethane Resin The obtained resin molded body was cut into a size of 10 mm length x 10 mm width x 10 mm thickness to obtain an evaluation sample. The volume V and weight W of the resin molded body were calculated using the following formula. In addition, the volume content V of calcium carbonate particles calculated by the firing method of JIS K7052 was calculated using the following formula. filler and the weight W of calcium carbonate particles filler , and the volume content V of the long glass fiber fiber and the weight W of the long glass fiber fiber The foaming ratio of the urethane resin was calculated using the following formula.

[0205] Volume V = vertical length of evaluation sample × horizontal length of evaluation sample × thickness of evaluation sample

[0206] Weight W = weight of evaluation sample

[0207] Foaming ratio of urethane resin = (1 - V filler -V fiber ) V / (W-W filler -W fiber )

[0208] V: Volume of resin molded body (cm ３ ) V filler V: volume content of calcium carbonate particles (volume %) fiber W: weight of resin molded body (g) filler W: Weight of calcium carbonate particles (g) fiber : Weight of long glass fiber (g)

[0209] (3) Acid Resistance The obtained resin molded article was cut into a size of 20 mm length x 20 mm width x 40 mm thickness to obtain an evaluation sample.

[0210] The following components were mixed to prepare an acid solution A having a pH of 3.5 and an acid solution B having a pH of 5.5. Each of the acid solutions A and B is an artificial acid rain solution.

[0211] <Acidic solution A (pH 3.5)> 5 wt% sodium chloride aqueous solution: 10 L Nitric acid: 0.012 L Sulfuric acid: 0.0173 L

[0212] <Acidic solution B (pH 5.5)> 5 wt% sodium chloride aqueous solution: 10 L Nitric acid: 0.00012 L Sulfuric acid: 0.000173 L

[0213] The evaluation sample was left for two weeks while being entirely immersed in acid solution A. Similarly, the evaluation sample was left for two weeks while being entirely immersed in acid solution B. The surface of the evaluation sample before immersion, the surface of the evaluation sample after immersion, and the cross section of the evaluation sample after immersion (cross section along the direction perpendicular to the thickness direction) were observed with a scanning electron microscope (SEM).

[0214] The distance D (average distance) over which the calcium carbonate particles had eluted was determined from a micrograph of the cross section of the evaluation sample after immersion. The distance D over which the calcium carbonate particles had eluted corresponds to the distance over which the acidic solution had penetrated.

[0215] After immersion, the evaluation sample was observed using a tabletop scanning electron microscope (JCM-7000), and elemental analysis was performed within the field of view.

[0216] The test using the acid solution A was carried out in Examples 1 to 3 and Comparative Examples 1 and 2. The test using the acid solution B was carried out in Example 1 and Comparative Example 1.

[0217] In addition, in the test using acid solution A, the compressive strength of the evaluation sample before and after immersion was measured by the following method.

[0218] Measurement method for compressive strength (compressive strength): The obtained resin molded product was cut into a size of length x width x thickness = 40 mm x 20 mm x 20 mm to obtain an evaluation sample. The length direction of the evaluation sample was aligned with the fiber direction. Before and after immersion, pressure was applied to the evaluation sample in the length direction at a test speed of 0.5 mm / min, and the maximum load at this time was divided by the cross-sectional area to obtain the compressive strength (compressive strength).

[0219] Details and results are shown in Tables 1-4 below and Figures 5-13.

[0220] Fig. 5 shows the results of a test using acid solution A in Example 1. Fig. 5(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution A, Fig. 5(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution A, Fig. 5(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution A, and Fig. 5(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution A.

[0221] Fig. 6 shows the results of a test using acid solution A in Example 2. Fig. 6(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution A, Fig. 6(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution A, Fig. 6(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution A, and Fig. 6(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution A.

[0222] Fig. 7 shows the results of a test using acid solution A in Example 3. Fig. 7(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution A, Fig. 7(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution A, Fig. 7(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution A, and Fig. 7(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution A.

[0223] Fig. 8 shows the results of a test using acid solution A in Comparative Example 1. Fig. 8(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution A, Fig. 8(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution A, Fig. 8(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution A, and Fig. 8(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution A.

[0224] Fig. 9 shows the results of a test using acid solution A in Comparative Example 2. Fig. 9(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution A, Fig. 9(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution A, Fig. 9(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution A, and Fig. 9(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution A.

[0225] Fig. 10 shows the results of a test using acid solution B in Example 1. Fig. 7(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution B, Fig. 10(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution B, Fig. 10(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution B, and Fig. 10(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution B.

[0226] Fig. 11 shows the results of a test using acid solution B in Comparative Example 1. Fig. 11(a) is a micrograph of the surface of the evaluation sample before immersion in acid solution B, Fig. 11(b) is a micrograph of the surface of the evaluation sample after immersion in acid solution B, Fig. 11(c) is a micrograph of the cross section of the evaluation sample after immersion in acid solution B, and Fig. 11(d) is the result of elemental analysis of the evaluation sample after immersion in acid solution B.

[0227] 12 shows the results of compressive strength tests of evaluation samples in Examples 1 to 3 and Comparative Examples 1 and 2 before and after immersion in acid solution A. In FIG. 12, "A" is Example 1, "B" is Example 2, "C" is Example 3, "X" is Comparative Example 1, and "Y" is Comparative Example 2.

[0228] FIG. 13 shows the results of the compressive strength reduction rate obtained by a compression test on the evaluation samples before and after immersion in the acid solution A in Examples 1 to 3 and Comparative Examples 1 and 2.

[0229]

[0230]

[0231]

[0232]

[0233] The second invention (and the first invention) will be specifically described below with reference to examples and comparative examples. The second invention (and the first invention) is not limited to the following examples. The following examples also correspond to examples of the first invention, and the following comparative examples also correspond to comparative examples of the first invention.

[0234] The following materials were prepared:

[0235] (Polyol Compounds) Polyether Polyol A ("DESMOPHEN V 883" manufactured by Sumika Covestro Urethane Co., Ltd., viscosity at 12°C: 500 cps) Polyether Polyol B ("J610" manufactured by Sumika Covestro Urethane Co., Ltd., viscosity at 25°C: 4500 cps)

[0236] (Isocyanate compound) Diphenylmethane diisocyanate ("Polymeric MDI" manufactured by Sumika Covestro Urethane Co., Ltd., viscosity 200 cps at 12°C)

[0237] The viscosity of the polyol compound and the isocyanate compound at 12°C was measured using a Brookfield viscometer ("Digital Rotational Viscometer" manufactured by Viscotec).

[0238] (Filler) Calcium carbonate particles ("Durcal 15" manufactured by Omya Corporation, specific gravity 2.7, average particle size 22 μm, surface untreated) Silica sand ("No. 7 silica sand" manufactured by Yamakawa Sangyo Co., Ltd., specific gravity 2.7, average particle size 190 μm)

[0239] (Reinforcing long fiber) Long glass fiber (a roving made by aligning many monofilaments with a fiber diameter of 6 to 20 μm)

[0240] (Foaming agent) Water

[0241] (Catalyst) Tertiary amine catalyst A (manufactured by Evonik Japan, "DABCO 33LV") Tertiary amine catalyst B (manufactured by San-Apro, "U-CAT SA1") Tin catalyst (manufactured by Nitto Kasei, "SCAT-31A")

[0242] (Foam stabilizer) Silicone oil A (manufactured by Evonik Japan Co., Ltd., "TEGOSTAB B 8404") Silicone oil B (manufactured by Toray Dow Silicon Co., Ltd., "SZ-1729")

[0243] Example 4 A foamed resin molded article was produced by the method shown in FIG.

[0244] <Preparation of Curable Resin Composition> A polyol compound, a foaming agent, a catalyst, and a foam stabilizer were mixed to obtain the first raw material shown in FIG. 2. The first raw material was mixed with a filler (calcium carbonate particles) to obtain a mixed solution A. An isocyanate compound, which is a second raw material, was added to and mixed with the obtained mixed solution A to obtain a first composition. The obtained first composition was impregnated between long glass fibers to prepare a curable resin composition. Each component was used in the blending amount (parts by weight) shown below.

[0245] Composition of curable resin composition: Polyether polyol A 100 parts by weight Diphenylmethane diisocyanate 123 parts by weight Calcium carbonate particles 170 parts by weight Long glass fibers 133 parts by weight Water 0.5 parts by weight Tertiary amine catalyst A 0.4 parts by weight Tertiary amine catalyst B 0.25 parts by weight Silicone oil A 0.9 parts by weight

[0246] <Preparation of resin molded article> The obtained curable resin composition was poured into a rectangular mold (length 400 mm × width 100 mm × height 65 mm), and then heated in an oven at 40°C for 50 minutes to foam-mold and harden, and a resin molded article (foamed resin molded article, thickness 140 mm) was obtained from the mold. The density of the obtained resin molded article was 0.85 g / cm ３ It was.

[0247] Comparative Example 3 Preparation of Curable Resin Composition Curable resin compositions were prepared by changing the types of ingredients used as shown below.

[0248] Composition of curable resin composition: Polyether polyol B 100 parts by weight Diphenylmethane diisocyanate 149.5 parts by weight Silica sand 76.4 parts by weight Long glass fiber 219 parts by weight Water 1.3 parts by weight Tin catalyst 0.2 parts by weight Silicone oil B 0.6 parts by weight

[0249] <Preparation of resin molded body> First, a mixture of components of the curable resin composition other than the long glass fibers was sprayed onto a bundle of long glass fibers, and the mixture was impregnated between the long glass fibers using a crumpling board. Then, the long glass fibers containing the mixture were passed through a molding passage (height 70 mm x width 230 mm), and were molded by being foamed and cured, to obtain a resin molded body (thickness 70 mm). The density of the obtained resin molded body was 0.71 g / cm ３ It was.

[0250] Comparative Example 4 Preparation of Curable Resin Composition Curable resin compositions were prepared by changing the types of ingredients used as shown below.

[0251] Composition of curable resin composition: Polyether polyol B 100 parts by weight Diphenylmethane diisocyanate 127 parts by weight Long glass fiber 229 parts by weight Water 1.0 part by weight Tertiary amine catalyst A 0.3 parts by weight Tertiary amine catalyst B 0.3 parts by weight Silicone oil B 0.6 parts by weight

[0252] <Preparation of resin molded body> A resin molded body (thickness 140 mm) was obtained in the same manner as in Comparative Example 3, except that the molding passage (height 150 mm x width 230 mm) was changed to a molding passage (height 140 mm x width 240 mm). The density of the obtained resin molded body was 0.74 g / cm ３ It was.

[0253] (Evaluation) (1) Volume Content of Filler (Calcium Carbonate Particles or No. 7 Silica Sand) and Long Glass Fiber The obtained resin molded body was cut into a size of 10 mm length × 10 mm width × 10 mm thickness. Using the cut resin molded body, the volume content of the filler (Calcium Carbonate Particles or No. 7 Silica Sand) in 100% by volume of the resin molded body and the volume content of the long glass fiber in 100% by volume of the resin molded body were determined in accordance with the firing method described in JIS K7052.

[0254] (2) Expansion Ratio of Urethane Resin The same evaluation as in "(2) Expansion Ratio of Urethane Resin" in Examples 1 to 3 and Comparative Examples 1 and 2 was carried out.

[0255] (3) Processability A woodworking drill (blade diameter: 8 mm, material: S45C) was attached to a bench drilling machine, and 50 holes were drilled in the resin molded body at a cutting depth of 50 mm at intervals of about 30 seconds per hole at a rotation speed of 550 rpm.

[0256] The weight of the woodworking drill was measured before and after cutting, and the weight loss was taken as the amount of wear of the drill. The less the amount of wear of the drill, the better the workability. Even a difference of just 0.01 g in the amount of wear of the drill makes a significant difference in workability.

[0257] (4) Bending Strength Resin molded bodies (thickness: 140 mm) were prepared in Example 4 and Comparative Example 4. In addition, a resin molded body (thickness: 140 mm) was prepared by laminating two resin molded bodies (thickness: 70 mm) in Comparative Example 3 together.

[0258] The dimensions of the resin molded bodies of Example 4 and Comparative Example 4 were length x width x thickness = 1400 mm x 240 mm x 140 mm. The dimensions of the resin molded body (bonded resin molded bodies) of Comparative Example 3 were length x width x thickness = 1400 mm x 230 mm x 140 mm. Evaluation was performed by a three-point bending test with a support distance of 1120 mm.

[0259] A support plate was placed on the support point. The dimensions of the support plate were length x width x thickness = 200 mm x 280 mm x 12 mm. The dimensions of the indenter of the loading section were length x width x thickness = 200 mm x 140 mm x 12 mm. The corner of the contact surface between the indenter and the resin molded body was R10, and the indenter was chamfered.

[0260] The test was carried out at a test speed of 2.0±0.5 mm / min until the resin molding broke. The three-point bending strength was calculated from the maximum strength, and this value was taken as the bending strength.

[0261] (5) Compression Strength The resin molded article was cut into a size of 40 mm x 20 mm x 20 mm to obtain an evaluation sample, with the length direction of the evaluation sample coinciding with the fiber direction.

[0262] Pressure was applied to the evaluation sample in the longitudinal direction at a test speed of 0.5 mm / min, and the maximum load at that time was divided by the cross-sectional area to obtain the compressive strength.

[0263] The results are shown in Table 5 below.

[0264]

[0265] The resin molded product obtained in Example 4 was also evaluated for the above-mentioned "(3) Acid resistance." As a result, the distance (D) over which calcium carbonate particles eluted after immersion in acid solution A was shorter in Example 4 than in Comparative Examples 1 and 2. Furthermore, the distance (D) over which calcium carbonate particles eluted after immersion in acid solution B was shorter in Example 4 than in Comparative Example 1.

[0266] DESCRIPTION OF SYMBOLS 1...Calcium carbonate particles 2...First raw material 3...Second raw material 4...Extruder 5...Mixing and spreading device 7...First composition 8...Reinforcing long fiber bundle 11...Hopper 12...Belt feeder 21...First raw material tank 22...Pump 31...Second raw material tank 43...Pump 51...Pump 61...Crumpling board 62...Impregnation board 63...Mold 81...Curable resin composition 91...Resin molded body 92...Urethane resin 93...Reinforcing long fiber 94...Calcium carbonate particles 100...Manufacturing device

Claims

1. A curable resin composition comprising a polyol compound, an isocyanate compound, reinforcing long fibers, and calcium carbonate particles, wherein the average particle size of the calcium carbonate particles is 8.5 μm or more, and the content of the calcium carbonate particles is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound.

2. The curable resin composition according to claim 1, wherein the calcium carbonate particles have an average particle size of 10 μm or more.

3. The curable resin composition according to claim 1 or 2, wherein the surfaces of the calcium carbonate particles are not treated with a surface treatment agent.

4. A curable resin composition according to any one of claims 1 to 3, wherein the reinforcing long fibers have a fiber length of 50 mm or more.

5. A curable resin composition according to any one of claims 1 to 4, wherein the content of the reinforcing long fibers is 40 parts by weight or more and 380 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound.

6. The curable resin composition according to any one of claims 1 to 5, wherein the reinforcing long fibers are long glass fibers.

7. A curable resin composition according to any one of claims 1 to 6, wherein the volume content of the calcium carbonate particles is 6 volume % or more and 19 volume % or less in 100 volume % of the curable resin composition.

8. The curable resin composition according to any one of claims 1 to 7, further comprising a foaming agent.

9. A resin molded body comprising a urethane resin, reinforcing long fibers, and calcium carbonate particles, the calcium carbonate particles having an average particle size of 8.5 μm or more, and the content of the calcium carbonate particles per 100 parts by weight of the urethane resin is 40 parts by weight or more and 240 parts by weight or less.

10. The resin molded article according to claim 9, wherein the calcium carbonate particles have an average particle size of 10 μm or more.

11. The resin molded article according to claim 9 or 10, wherein the surfaces of the calcium carbonate particles have not been treated with a surface treatment agent.

12. A resin molded body according to any one of claims 9 to 11, wherein the volume content of the calcium carbonate particles is 6 volume % or more and 19 volume % or less, based on 100 volume % of the resin molded body.

13. The resin molding according to any one of claims 9 to 12, wherein the reinforcing long fibers have a fiber length of 50 mm or more.

14. The resin molding according to any one of claims 9 to 13, wherein the reinforcing long fibers are long glass fibers.

15. A resin molded body according to any one of claims 9 to 14, wherein the volume content of the calcium carbonate particles is 6 volume % or more and 19 volume % or less, based on 100 volume % of the resin molded body.

16. The resin molded article according to any one of claims 9 to 15, which is a foamed resin molded article.

17. The resin molded article according to claim 16, wherein the foaming ratio of the urethane resin is 1.1 times or more and 5 times or less.

18. The resin molded article according to any one of claims 9 to 17, which is a railroad tie.

19. A method for producing a resin molded product according to any one of claims 9 to 18, comprising: a step of obtaining a first composition containing a polyol compound, an isocyanate compound, and calcium carbonate particles; an impregnation step of impregnating spaces between reinforcing long fibers with the first composition to obtain a curable resin composition; and a curing step of curing the curable resin composition in a mold, wherein the content of the calcium carbonate particles in the first composition is 40 parts by weight or more and 240 parts by weight or less per 100 parts by weight of the total of the polyol compound and the isocyanate compound in the first composition.

20. The method for producing a resin molding according to claim 19, wherein the reinforcing long fibers have a fiber length of 50 mm or more.

21. A method for producing a resin molded body described in claim 19 or 20, wherein in the impregnation step, the first composition is impregnated between the reinforcing long fibers so that the content of the reinforcing long fibers is 20 parts by weight or more and 150 parts by weight or less per 100 parts by weight of the first composition.

22. The method for producing a resin molded article according to any one of claims 19 to 21, wherein the reinforcing long fibers are long glass fibers.

23. A method for producing a resin molded product according to any one of claims 19 to 22, wherein the first composition contains a foaming agent, and in the curing step, the curable resin composition is foamed and cured in a mold.

24. The method for producing a resin molded article according to any one of claims 19 to 23, which is a method for producing a resin molded article to be used as a sleeper.

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